.beta.-Damascenone, an alicyclic ketone of formula ##STR7## is particularly well appreciated in the art of perfumery and flavors. Its utilization as perfuming and flavoring ingredient is the object of several patents, viz. U.S. Pat. No. 3,975,310, Swiss Pat. Nos. 520,479 and 509,399. Many syntheses have been proposed in the past for preparing .beta.-damascenone, the most interesting ones being cited hereinafter:
dehydrogenation of the corresponding cyclohexenic compound, viz. .beta.-damascone (see Swiss Pat. No. 505,773); PA0 treatment of 1-(2,6,6-trimethyl-1,2-epoxy-cyclohexyl)-but-2-en-1-one with an acidic dehydrating agent (see DE-AS No. 20 65 322), and PA0 treatment of 4-(2,6,6-trimethyl-1-hydroxy-cyclohex-2-en-1-yl)-but-3-yn-2-ol with an acidic dehydrating agent (see DE-PS No. 22 42 751).
Despite the existence of several synthetic methods there exists the constant need to improve the yield of the existing methods or to elaborate new and original syntheses, namely syntheses starting from cheaper or more accessible raw materials. The invention provides an efficient solution to this problem.